Despite using https://en.bildelsbasen.se things weren’t
Utan anmärkning as described.
We found some engine parts filled with water (which by the way means the generator no longer works so we took it from the old engine). It was also very clean : not a single stain.
As if the whole engine was plunged in water in order to be cleaned. (though outside and internals were dry).
The engine starts but with a lot of water smoke and coolent level is decreasing. Compression is 30% below normal for the top left cylinder to 90% below normal for the top right cylinder (each cylinder has compression lower than the previous one).
So looks like head gasket is damaged (though even after running 5 minutes temperature stay cool). If it’s just that, it might worth to buy a new one for 50€, but if a piston ring is damaged, it would cost over 500€ in parts to replace it (which means changing the engine again would be a better idea).
So how to check for damaged piston ring in such situation in order to avoid spending over 200€ for removing cylinder head ?